1. Field of the Invention
The invention relates generally to solid state imaging devices and more particularly to solid state imaging devices having enhanced blue light sensitivity.
2. Description Relative to the Prior Art
Solid state imaging devices are well known, and have in the last few years aroused great interest with the advent of charge-transfer-type devices. One problem with using these charge-transfer-type devices for high quality imaging has been their low sensitivity to blue light. Such blue insensitivity typically occurs because image light passes through polysilicon electrodes before reaching the layer of the device where image representative electrical charges are formed. While polysilicon is for the most part transparent to visible light it does, unfortunately, attenuate short wavelength visible light to a large degree. In fact, polysilicon is almost opaque to violet-blue light.
Because of this undesirable blue absorption characteristic of polysilicon, substantial research efforts have been directed toward the development of a superior material for imaging device electrodes. Such efforts have met with considerable difficulties, however, as a result of stringent requirements as to, for example, transparency, compatability with adjacent layer materials, and electrical conductivity.